rounds



(No Model.)

J. G. ROUNDS.

MECHANICAL TELEPHONE.

No. 318,397. Patented May 19, 1885.

MA msx irmm.

ISIEEEEE UNITED STATES PATENT OFFICE.

JOHN C. ROUNDS, OF MORAVIA, NEIV YORK.

MECHANICAL TELEPHONE.

SPECIFICATION forming part of Letters Patent No. 318,397, dated May 19,1885.

Application filed April 29, 1884. (No model.)

To all whom it may concern.-

Be it known that I, JOHN C. RoUNDs, a citizen of the United States,residing at Moravia, in the county of Cayuga and State of New York, haveinvented certain new and useful Improvements in Mechanical Telephones;and I do declare the following to be a full, clear, and exactdescription of the invention, such as will enable others skilled in theart to which it appertains to make and use the same, reference being hadto the accompanying drawings, and to the letters and figures ofreference marked thereon, which form a part of this specification.

My invention relates to telephones of the class known as mcchanical,-and has for its object to so construct the receiver as to overcome oravoid the roaring incident to devices of its class, and to enable therapid transmission of sound by rendering clear and distinct eachsyllable as uttered.

To this end it consists in the novel construction hereinafter described.

In the accompanying drawings, Figure l is a transverse section of myreceiver. Fig. 3 is a front view of same with the diaphragm removed.Fig. 2 is a back view of the diaphragm-supporting plate, illustratingthe manner of securing the diaphragm thereon, as will be hereinaftermore fully described.

The mouth of the receiver-box is formed with a flange or ring, A, fromthe rear edge of which is bent inward the circular concave plated, inthe center of which is formed an opening, a, for the line-wire. The caseB is composed of annular plate or ring 13 and the back plate, B throughwhich is formed the line-wire opening I). The ring B is made preferablyof a less diameter than ring A, and is soldered or otherwise secured toback of concave plate a, as clearly shown in Fig. 1. Thediaphragm-supporting plate 0 is made of a diameter equal the plate a,and is concave, as shown, though at not so great an angle as plate a. Itis seated within ring A, as shown in Fig. 1. This plate 0 is providedwith a central opening, D, and the central or apex portion of the plate0 is extended into the opening a of plate a, which opening is madelarger than the opening D, as most clearly shown in Fig. 1. The openingsD and b are made of about the same size and sufficiently large to permitthe passage of the line-wire without affecting the vibrations of same.The diaphragm E has its edges 0 turned over the edge of plate 0 andsecured thereto in any suitable manner, preferably by means of stitching6, as shown in Fig. 2. I by preference make this diaphragm of oil-tannedleather or other suitable soft pliable material, and secure thenecessary resonance by proper stretching of same, either by the tensionof the linewire F or by the degree of tightness with which the diaphragmis stretched into place on its supporting-plates O. The line-wire F ispassed through openings 1) a D and the diaphragm, and is secured to thelatter by means of a suitable button, f, which I preferably make of leador other suitable non-resonant material. This diaphragm, being made ofsoft pliable material, will not respond to or echo the roaring soundscommon to such devices when made of metal or hard dried skins, and yetwill readily give off the sounds imparted to it by the direct impulse ofthe wire.

I prefer in practice to secure the diaphragm by crimping its edge over asupporting-plate and securing it, thus securely fastening the diaphragm,and so protecting its supportingplate as to prevent any vibration orrattling thereof in its casing. By the described construction the case Bforms a chamber, G, into which the plate a tits. Between the plates aand O, I form a chamber, H. These chambers H and G are between thediaphragm and the outer air, and serve to exhaust the externalvibrations, so that such vibrations reach the diaphragm, if at all, inbut a lessened degree.

Having described my invention, what I claim, and desire to secure byLetters Patent, 1s

1. The combination, in a mechanical-telephone receiver, of the ring B,plate B the concave plate a, the diaphragm, and the diaphragm-supporting plate 0, said plates B (1, and 0 being arrangedsubstantially as described, whereby air-chambers G and H are interposedbetween the diaphragm and the external air, substantially as set forth.

2. The herein-described mechanical-telephone receiver, composed ofconcave plate a, having central opening, a, the ring B, and

said middle portion being extended into the opening a, substantially asset forth. 10

I11 testimony whereof I affix my signature in plate B, the diaphragm,the line, and the plate presence of two witnesses. 5 C, supporting thediaphragm and having its outer edges resting on the outer edges of theXVitnesses:

plate a, and its middle portion perforated with J. S. MAHEY,

air-opening smaller than the opening a, the J. H. HARRIS.

JOHN C. ROUNDS.

